Dynamically hide, default, copy, clear, validate, set ticket fields

NOTE: I suggest you use the 0.11 branch only even for Trac 0.12 installations. The Trac 0.12 branch has some issues. The plan is to merge the two branches to support both Trac 0.11 and 0.12 on one branch. Thanks. - robguttman

Description

This plugin dynamically changes fields in ticket views based on simple rules using JavaScript / jQuery (required for this plugin). Example dynamic behavior:

Fields that are always hidden will also be hidden on the custom query (/query) page. The clear_on_hide option above specifies that the field's value should not be cleared when hidden (clearing is the default behavior). Sometimes you want to allow users to get access to hidden fields. You can enable specific fields to be shown in ticket views when a user clicks a "Show hidden fields" link:

The default is that hidden fields are not enabled to be shown (i.e., link_to_show defaults to false). The "Show hidden fields" link is only shown when there are hidden fields and at least one of them is enabled to be shown.

Clear rule

In the version/milestone example above, if the milestone changes then we want the version field to be cleared:

[ticket-custom]
version.clear_on_change_of = milestone

Note that 'clearing' a select field will actually reset it to its default value if no 'empty' option is available.

Copy rule

Let's say your workflow includes reassigning a ticket's owner to someone else for review or verification but maintain the person responsible for the work in a custom captain field. Initially the captain should be set to the owner, so to reduce data entry in making this so:

[ticket-custom]
captain.copy_from = owner

The default copy behavior is to not overwrite a value if one already exists. To always copy the value, add (overwrite) as follows:

[ticket-custom]
captain.copy_from = owner (overwrite)

Default rule

Let's say your QA team usually creates defect tickets and your product managers usually create enhancement tickets. Here's how to allow each user to set the default value for the ticket type:

[ticket-custom]
type.default_value = (pref)

For text fields, if the field's value is not empty, the default value will not be applied unless you set an append option to true:

[ticket-custom]
cc.default_value = (pref)
cc.append = true

Using append presumes the field is a comma-delimited list and will append any missing values from the default preference value (which can also be a comma-delimited list) to that field's list.

Validate rule

Some fields may be required (i.e., can't be empty) or must not contain some specific values. For example:

[ticket-custom]
owner.invalid_if =
severity.invalid_if = pick one

The above will prevent the ticket from being submitted if either the owner field is empty or the severity field's value equals pick one. The value for the invalid_if rule can be empty or any regular expression. Hidden fields do not get validated.

Set rule

When a developer starts working on a ticket, you may want to make sure she sets the milestone accordingly:

When the phase field changes to either implementation, verifying, or releasing, then the milestone will get set to milestone3. To avoid needing to update the current milestone's value in the rule, you can alternatively use the special "!" value which specifies to set the field to the first non-empty value:

milestone.set_to_!_when_phase = implementation|verifying|releasing

If you want to enable each user to set the value as a preference, you set to an asterisk * as follows:

User preferences

Any rule expressed above can be configured to allow users to set preferences for them by appending (pref) to the end of the rule. For example, here's one of the hide rules from above:

[ticket-custom]
alwayshidden.show_when_type = invalid_value (pref)

The (pref) will cause this rule to be added to a new Dynamic Fields preference panel where the user can disable the rule by unchecking the rule's checkbox. Some rules require user input such as the default value rule above. In that example, the user can both enable/disable the rule as well as set the field's default value for him/her. If you wish to disable a rule as the default preference, append (pref:disable) to the end of the rule like so:

Extensibility (implementation details)

Rules are implemented as Trac extension points to allow for new rules to be added fairly easily. Six rules come packaged to provide the dynamic behaviors described above. Each rule is split between two parts:

rule specification (Python in rules.py)

rule implementation (JavaScript in rules.js)

The two parts are linked by instantiating the JavaScript part with the class name of the python part. See the code for details. JavaScript was chosen over Genshi transforms to dynamically have fields change without requiring a form submission - hence the plugin's name, Dynamic Fields.

About i18n/l10n support

The 0.12 branch of this plugin is prepared for localization.
But English message texts are still the (POSIX) default. If this isn't your preferred language, you can

Preparing the plugin from source now requires the additional step of compiling message catalog files. As long as you stick to the message catalogs served with this plugin directly, there is still nothing special to be done. Just package your plugin from source the standard way:

cd dynamicfieldsplugin
python ./setup.py bdist_egg

and the proper helper function calls to a suitable Babel install will be issued automatically for you. Beware, there is a ​Trac ticket strongly suggesting to do Babel install before Trac 0.12 install, or your Babel will not be functional with Trac. You're hit by this bug, if your message compilation does not produce any usable catalog.

Only if you encounter message catalogs with translations marked 'fuzzy', including them would require special treatment, since automatic compilation trashes them by default. Walk through: